CN113613975A

CN113613975A - Air supply circuit

Info

Publication number: CN113613975A
Application number: CN201980093013.9A
Authority: CN
Inventors: 板谷将治; 松家伸成
Original assignee: Nabtesco Automotive Corp
Current assignee: Nabtesco Automotive Corp
Priority date: 2018-12-28
Filing date: 2019-12-27
Publication date: 2021-11-05
Also published as: JPWO2020138394A1; JP7438979B2; WO2020138394A1

Abstract

Provided is an air supply circuit capable of maintaining the operating state of a parking brake even if an electronic control device for controlling the parking brake loses power. The air supply circuit (10) is provided with: a supply flow path (50) having a relay valve (40) between the air tank (13) and a brake chamber for a parking brake, the supply flow path (50) being used for supplying air; a signal circuit (60) in which a normally closed first solenoid valve (41) and a normally closed second solenoid valve (42) are arranged in series between a gas tank (13) and a release circuit (39) that is open to the atmosphere, the signal circuit (60) being for transmitting an air pressure signal; and an ECU (21) that controls the switching of the opening and closing of the first electromagnetic valve (41) and the switching of the opening and closing of the second electromagnetic valve (42), respectively. An air pressure signal between the first solenoid valve (41) and the second solenoid valve (42) is applied to the relay valve (40) as a control pressure signal for controlling the relay valve (40).

Description

Air supply circuit

Technical Field

The present invention relates to an air supply circuit for supplying air to a brake mechanism of a vehicle.

Background

A vehicle is provided with an air pressure brake system including a Service brake (Service brake) mechanism (foot brake mechanism) and a parking brake mechanism. The air pressure brake system includes an air supply circuit that supplies compressed air from a compressor and supplies the dried compressed air to the parking brake mechanism. Recently, an air supply circuit provided with an electronic control device and controlled by the electronic control device has been proposed (for example, see patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2007-326516

Disclosure of Invention

Problems to be solved by the invention

However, in the above system, it is not considered to maintain the parking brake in an appropriate operating state when the electronic control unit loses power.

The invention aims to provide an air supply circuit which can maintain the operation state of a parking brake even if an electronic control device for controlling the parking brake loses power supply.

Means for solving the problems

The air supply circuit for achieving the above object includes: a supply flow path having a relay valve between the air tank and a brake chamber for parking brake, the supply flow path supplying air; a signal circuit having a normally closed first solenoid valve and a normally closed second solenoid valve arranged in series between the gas tank and a release circuit open to the atmosphere, the signal circuit being for transmitting an air pressure signal; and a control device that controls switching of opening and closing of the first electromagnetic valve and switching of opening and closing of the second electromagnetic valve, respectively, wherein an air pressure signal between the first electromagnetic valve and the second electromagnetic valve is applied to the relay valve as a control pressure signal for controlling the relay valve.

In this case, since the first solenoid valve and the second solenoid valve are normally closed solenoid valves, when the control device that controls the opening/closing of these solenoid valves loses power, the air pressure between the first solenoid valve and the second solenoid valve immediately before the loss of power is maintained as the pressure of the air pressure signal between the first solenoid valve and the second solenoid valve. Therefore, the operation of the relay valve, which inputs the air pressure signal as the control pressure signal, is maintained. Thus, even if the control device for controlling the parking brake loses power, the operating state of the parking brake can be maintained.

In one embodiment, there may be a release valve capable of releasing the control pressure signal applied to the relay valve to atmosphere.

In this case, the parking brake held in the released state by the air pressure signal having the pressure of the compressed air can be set in the activated state by the operation of the release valve.

In one embodiment, an air pressure maintaining mechanism may be provided between the first solenoid valve and the relay valve, the air pressure maintaining mechanism causing no transmission of air pressure from the first solenoid valve to the relay valve when the first solenoid valve is closed.

The parking brake is released by an increase in air pressure and operated by a decrease in air pressure to atmospheric pressure. In this regard, in this case, there is no possibility that the parking brake is released due to an increase in air pressure when the first solenoid valve is closed.

In one embodiment, the signal circuit may be provided with a check valve that allows air to flow from the first solenoid valve disposed on the tank side to the second solenoid valve disposed on the release circuit side, the control pressure signal may be an air pressure signal between the check valve and the second solenoid valve, and the first solenoid valve may be a three-way valve that opens a space between the first solenoid valve and the check valve to the atmosphere when the first solenoid valve is closed.

In this case, although the first solenoid valve is a three-way valve, the check valve can keep the air pressure on the second solenoid valve side higher than the air pressure on the first solenoid valve side, and therefore, even if the first solenoid valve and the second solenoid valve are closed due to the loss of the power supply of the control device, the pressure of the air pressure signal is maintained to be the same before and after the loss of the power supply.

When the first solenoid valve is closed, even if compressed air leaks from the first solenoid valve, the leaked compressed air is guided to the port of the first solenoid valve that is open to the atmosphere by the sealing force of the check valve. This prevents the air pressure on the second solenoid valve side from rising, and prevents the parking brake once in the activated state from being suddenly released. That is, the air pressure holding mechanism is constituted by the check valve and the second electromagnetic valve.

In one embodiment, the signal circuit may have a quick release valve, the air pressure signal may be applied as the control pressure signal to the relay valve via the quick release valve when the air pressure signal has an air pressure above a working pressure of the quick release valve, and atmospheric pressure may be applied as the control pressure signal to the relay valve via the quick release valve when the air pressure signal has an air pressure less than the working pressure of the quick release valve.

In this case, when the first solenoid valve and the second solenoid valve are closed due to the loss of power to the control device, the control pressure signal to the relay valve is maintained in a state before the loss.

In addition, when the first solenoid valve is closed, even if compressed air leaks from the first solenoid valve, the control pressure signal is maintained at atmospheric pressure as long as the air pressure signal between the first solenoid valve and the second solenoid valve does not rise to the operating pressure of the quick release valve. Further, even if air pressure equal to or lower than the operating pressure is slowly applied to the quick release valve, the control pressure signal does not rise to the operating pressure because the air pressure leaks to the release circuit. That is, the air pressure maintaining mechanism is constituted by a quick release valve.

In one embodiment, the air supply circuit may be connected to a brake chamber of a tractor and a trailer control valve, the signal circuit having a third solenoid valve, the signal circuit outputting the air pressure signal to the trailer control valve and applying the air pressure signal to the relay valve via the third solenoid valve, the air supply circuit supplying compressed air regulated by the relay valve to the brake chamber of the tractor.

In this case, the operating state of the parking brake of the tractor and the operating state of the parking brake of the trailer can be set to different states. For example, by interrupting the air pressure signal to the relay valve by the third solenoid valve, only the parking brake of the trailer can be released in a state where the parking brake of the tractor is activated, and only the parking brake of the tractor can be checked. Here, the parking brake of the trailer includes a parking brake using a service brake of the trailer.

In one embodiment, the third electromagnetic valve may be a normally closed electromagnetic valve, and the control device may control switching between opening and closing of the third electromagnetic valve.

In this case, since the third electromagnetic valve is a normally closed electromagnetic valve, even if air leaks from the first electromagnetic valve when the control device that controls the opening/closing of the electromagnetic valve loses power, the air pressure signal can be prevented from being applied to the relay valve by the normally closed third electromagnetic valve.

In one embodiment, it may be that the air pressure signal is output to the trailer control valve via a quick release valve.

In this case, the air pressure signal is supplied to the trailer control valve via the quick release valve. When compressed air is not supplied to the trailer control valve, even if a pressure lower than the operating pressure is applied to the air pressure signal due to leakage of compressed air from the first solenoid valve, the quick release valve is opened to the atmosphere, and thus the parking brakes in the tractor and the trailer are not released.

Drawings

Fig. 1 is a circuit diagram showing a schematic configuration of a first embodiment embodying an air supply circuit.

Fig. 2 is a circuit diagram showing a schematic configuration of a second embodiment embodying an air supply circuit.

Fig. 3 is a circuit diagram showing a schematic configuration of a third embodiment embodying an air supply circuit.

Fig. 4 is a circuit diagram showing a schematic configuration of a fourth embodiment embodying an air supply circuit.

Fig. 5 is a circuit diagram showing a schematic configuration of a fifth embodiment embodying an air supply circuit.

Fig. 6 is a circuit diagram showing a schematic configuration of another embodiment embodying the air supply circuit.

Fig. 7 is a circuit diagram showing a schematic configuration of another embodiment embodying the air supply circuit.

Fig. 8 is a circuit diagram showing a schematic configuration of another embodiment embodying the air supply circuit.

Fig. 9 is a circuit diagram showing a schematic configuration of another embodiment embodying the air supply circuit.

Fig. 10 is a circuit diagram showing a schematic configuration of another embodiment embodying the air supply circuit.

Detailed Description

(first embodiment)

Fig. 1 shows a first embodiment in which an air supply circuit 10 is applied to a parking brake mechanism of a tractor (not shown) as a vehicle. The parking brake mechanism uses compressed dry air as a driving source. A tractor is a vehicle that can be coupled to a trailer. That is, the trailer can be coupled to the tractor.

In general, a tractor is provided with a service brake mechanism and a parking brake mechanism. The service brake is operated by supplying air to the service brake mechanism, and the service brake is released (not operated) when air is discharged from the service brake mechanism. When air is supplied to the parking brake mechanism, the parking brake is released, and when air is discharged from the parking brake mechanism, the parking brake is operated. The air supply circuit 10 is a circuit applied to a parking brake mechanism.

As shown in fig. 1, the air supply circuit 10 adjusts the supplied compressed air and supplies the adjusted compressed air to a brake chamber of a tractor or a control valve of a trailer.

The tractor includes an air tank 13 and an air supply circuit 10, and the air tank 13 stores dry and purified air supplied from a compressor (not shown) driven by an engine (not shown). The air supply circuit 10 adjusts compressed air supplied from the air tank 13 via the 13 th port P13, and supplies the adjusted compressed air to the 21 st port P21 and the 22 nd port P22, thereby releasing or actuating the parking brake of the tractor via the 21 st port P21 and the 22 nd port P22.

A Trailer Control Valve (TCV) is connected to the 31 st port P31 of the air supply circuit 10. The trailer control valve releases or operates the parking brake of the trailer by controlling the supply and discharge of air to and from the air pressure circuit of the trailer. Note that, although the parking brake of the trailer is referred to as a service brake using the trailer, the parking brake of the trailer will be described below for convenience of description.

The structure of the air supply circuit 10 will be described.

In the air supply circuit 10, a plurality of wires E61 to E66 are connected to the ECU21 as a control device. Further, description of other wirings is omitted. The ECU21 includes a calculation unit, a volatile storage unit, and a nonvolatile storage unit, and the ECU21 supplies the command value to the air supply circuit in accordance with a program stored in the nonvolatile storage unit. The ECU21 is connected to other control devices such as a vehicle ECU via a wiring E61 as a communication line of the in-vehicle LAN and the like so as to be able to transmit vehicle information to and from these control devices.

The air supply circuit 10 includes: a supply flow path 50 for mainly supplying compressed air from the gas tank 13 to the ports P21 and P22; and a signal circuit 60 for mainly transmitting an air pressure signal for adjusting the air pressure supplied to the parking brake.

The supply flow path 50 is a flow path from the 13 th port P13 to the 21 st port P21 and the 22 nd port P22, and includes a relay valve 40 and a branch portion branching off to the 21 st port P21 and the 22 nd port P22 in the middle of the flow path. The first flow path 51 extends from the 13 th port P13 to the input of the relay valve 40, the second flow path 52 extends from the output of the relay valve 40 to the branch portion, the third flow path 53 extends from the branch portion to the 21 st port P21, and the fourth flow path 54 extends from the branch portion to the 22 nd port P22.

The signal circuit 60 is used to transmit an air pressure signal for adjusting the intensity of the parking brake to the relay valve 40 and to the trailer control valve via the 31 st port P31. The relay valve 40 releases or operates the parking brake of the tractor based on the air pressure signal. The trailer control valve deactivates or activates the parking brake of the tractor based on the air pressure signal.

The signal circuit 60 is a circuit from the 13 th port P13 to the relief circuit 39, and includes the first solenoid valve 41, the check valve 45, the third solenoid valve 43, and the second solenoid valve 42 in this order from the upstream of the circuit. The first circuit 61 extends from the 13 th port P13 to the input of the first solenoid valve 41, the second circuit 62 extends from the output of the first solenoid valve 41 to the input of the check valve 45, the third circuit 63 extends from the check valve 45 to the third solenoid valve 43, the fourth circuit 64 extends from the third solenoid valve 43 to the second solenoid valve 42, and the outlet of the second solenoid valve 42 is connected to the release circuit 39. The third circuit 63 is branched and connected to a sixth circuit 66 connected to a 31 st port P31 and a signal air pressure sensor (PU)47 for detecting air pressure. The fourth circuit 64 is branched and is also connected to a fifth circuit 65 to which the relay valve 40 is connected. The fifth circuit 65 is connected to the relief valve 101 via a 101 th port P101. The relief circuit 39 communicates with an exhaust port 49 opened to the atmosphere. The release valve 101 may be a manual valve that can be operated even when the ECU21 loses power, or may be a valve that can be operated by another control device such as a vehicle ECU.

The check valve 45 allows the compressed air to flow in a direction (an allowable direction) from the second circuit 62 to the third circuit 63. On the other hand, the check valve 45 prohibits the supply of compressed air in the direction from the third circuit to the second circuit 62 (prohibited direction). The check valve 45 has a sealing force that does not allow air at a pressure lower than a predetermined pressure to flow therethrough even if the air flows in the allowable direction.

The ECU21 is connected to the first solenoid valve 41 via a wiring E62, the third solenoid valve 43 via a wiring E64, and the second solenoid valve 42 via E65. The ECU21 is connected to the signal air pressure sensor 47 via a wiring E63, and is connected to the supply air pressure sensor 48 via a wiring E66. The ECU21 can acquire the air pressure of the signal circuit 60 from the signal air pressure sensor 47, and can acquire the air pressure of the supply flow path 50 from the supply air pressure sensor 48.

The first solenoid valve 41, the second solenoid valve 42, and the third solenoid valve 43 are two-position solenoid valves that are switched by turning on and off of a power supply under the control of the ECU 21. Next, the state in which the power supply is turned off is described as "off", and the state in which the power supply is turned on is described as "on".

The first solenoid valve 41 is a normally closed three-way two-position solenoid valve, and is controlled to be opened/closed via a wiring E62. The first solenoid valve 41 is disposed in a sealing position shown in fig. 1 when closed, and disposed in a communication position when opened. The first solenoid valve 41, when in the sealed position, shuts off communication between the first and

second circuits

61, 62 and communicates the second circuit 62 with the relief circuit 39. The first solenoid valve 41 communicates the first circuit 61 with the second circuit 62 when in the communication position, and cuts off communication between the second circuit 62 and the relief circuit 39.

The second solenoid valve 42 is a normally closed two-way two-position solenoid valve, and is controlled to be opened/closed via a wiring E65. The second solenoid valve 42 is disposed in the sealing position shown in fig. 1 when closed, and disposed in the communication position when opened. The second solenoid valve 42 shuts off communication between the fourth circuit 64 and the relief circuit 39 in the sealing position, and communicates the fourth circuit 64 with the relief circuit 39 in the communication position.

The third solenoid valve 43 is a solenoid valve for releasing only the parking brake of the trailer for inspection. The third solenoid valve 43 is normally maintained closed and is opened at the time of inspection. The third solenoid valve 43 is a normally open two-way two-position solenoid valve, and is controlled to be opened/closed via a wiring E64. The third solenoid valve 43 is disposed in the communication position shown in fig. 1 when closed, and is disposed in the sealing position when opened. The third solenoid valve 43 blocks communication between the third circuit 63 and the fourth circuit 64 in the sealed position, and communicates the third circuit 63 and the fourth circuit 64 in the communication position.

The operation of the air supply circuit 10 will be described.

First, when the parking brake is changed from an activated state (on state) to a deactivated state (off state), the ECU21 opens the first solenoid valve 41 and closes the third solenoid valve 43 and the second solenoid valve 42. As a result, an air pressure signal based on the air pressure of the compressed air from the tank 13 is maintained in the second circuit 62, the third circuit 63, and the fourth circuit 64, and the relay valve 40 is operated by the air pressure signal of the fourth circuit 64 via the fifth circuit 65. The relay valve 40 supplies the compressed air from the air tank 13 to each brake chamber via the second flow path 52, the third flow path 53, and the fourth flow path 54. The ECU21 detects the air pressure in the third circuit 63 by the signal air pressure sensor 47, and detects the air pressures in the third flow path 53 and the fourth flow path 54 by the supply air pressure sensor 48. When the detected pressures of the signal air pressure sensor 47 and the supply air pressure sensor 48 reach the respective target pressures, the ECU21 closes the first solenoid valve 41 and opens the second solenoid valve 42 to set the pressures of the air pressure signals of the second to fifth circuits 62 to 65 to the atmospheric pressure. On the other hand, when the detected pressure of either one of the signal air pressure sensor 47 and the supply air pressure sensor 48 is less than the corresponding target pressure, the ECU21 opens the first electromagnetic valve 41 after closing the second electromagnetic valve 42, and sets the pressure of the air pressure signal to the pressure of the compressed air from the air tank 13. Accordingly, the air pressure in the second flow path 52, the third flow path 53, and the fourth flow path 54 is adjusted to be maintained at the target pressure, and the compressed air of a predetermined pressure is supplied to the brake chamber to release the parking brake of the tractor. Further, compressed air of a target pressure is supplied to the trailer control valve to release the parking brake of the trailer.

Further, the ECU21 may control the opening/closing of the first electromagnetic valve 41 and the second electromagnetic valve 42 based on the detected pressure of either one of the signal air pressure sensor 47 and the supply air pressure sensor 48. Further, the ECU21 may learn, from the signal air pressure sensor 47, the air pressure required by the signal circuit 60 in order to set the detected air pressure supplied to the air pressure sensor 48 to the target air pressure.

Next, when the parking brake is changed from the released state to the activated state, the ECU21 closes the first solenoid valve 41 and the third solenoid valve 43 and opens the second solenoid valve 42. Thereby, the third circuit 63 and the fourth circuit 64 are connected to the relief circuit 39, and the pressure of the air pressure signal is maintained at the atmospheric pressure. The atmospheric pressure signal deactivates the relay valve 40, and compressed air is not supplied from the second flow path 52, the third flow path 53, and the fourth flow path 54 to the brake chamber, so the brake chamber activates the parking brake. The ECU21 detects the air pressure in the third circuit 63 by the signal air pressure sensor 47, and detects the air pressures in the third flow path 53 and the fourth flow path 54 by the supply air pressure sensor 48. The ECU21 confirms whether the detected pressures of the signal air pressure sensor 47 and the supply air pressure sensor 48 are atmospheric pressures, respectively. The ECU21 may close the second electromagnetic valve 42 when the detected pressure is atmospheric pressure. At this time, when the detected pressure of either one of the signal air pressure sensor 47 and the supply air pressure sensor 48 is no longer at atmospheric pressure, the ECU21 opens the second electromagnetic valve 42 to bring the detected pressure to atmospheric pressure. Thereby, the air pressure of the third flow passage 53 and the fourth flow passage 54 is maintained at the atmospheric pressure. Thus, the brake chamber is maintained at atmospheric pressure, thereby operating the parking brake of the tractor. Further, the air pressure of the trailer control valve is set to the atmospheric pressure, and the parking brake of the trailer is operated.

In addition, the air supply circuit 10 can release only the parking brake of the trailer for inspection. In the inspection, the ECU21 first opens the second solenoid valve 42 and closes the third solenoid valve 43 to set the parking brake of the tractor and the trailer in an operating state (on). Then, the third solenoid valve 43 is opened to maintain the air pressure in the fourth circuit 64, whereby the operation state of the parking brake of the tractor is maintained. Next, when the first solenoid valve 41 is opened, compressed air is supplied to the port P31 via the third circuit 63 and the sixth circuit 66, and the parking brake of the trailer is released. During the inspection, even if the power supply is lost, the state in which only the parking brake of the tractor is operated can be maintained. This allows the parking brake of the trailer to be released, and only the parking brake of the tractor can be checked. The check here is a check as to whether or not the tractor to which the trailer is connected can be kept in a stopped state on a slope having a gradient of 12% only by the parking brake of the tractor in a state where the parking brake of the trailer is released.

The operation of the present embodiment will be described.

In addition, in the ECU21, the power supply may be lost due to disconnection or the like. At this time, it is necessary to maintain the released state or the operated state of the parking brake at the time of loss of power supply to avoid the operation state of the parking brake from being different from the operation by the driver immediately before the loss of power supply. That is, it is necessary to prevent the parking brake from being switched from the released state to the actuated state or from being switched from the actuated state to the released state due to the loss of power to the ECU 21. In this regard, according to the present embodiment, even if the ECU21 loses power due to disconnection or the like, the operating state of the parking brake is maintained as the operating state at the time of loss of power. In the following description, when the trailer parking brake is not checked, the normally-open third solenoid valve 43 is opened to communicate the third circuit 63 with the fourth circuit 64.

First, a case where the ECU21 loses power when the parking brake is in an operating state will be described.

Immediately before the power loss, the first solenoid valve 41 is closed, the second solenoid valve 42 is opened or closed after being opened to the atmosphere, and thus the second circuit 62, the third circuit 63, and the fourth circuit 64 are all opened to the atmosphere. When the power is lost at this time, both the normally closed first solenoid valve 41 and second solenoid valve 42 are closed to become closed, and the atmospheric pressure immediately before the power is lost is maintained in the third circuit 63 and fourth circuit 64 interposed between the check valve 45 and second solenoid valve 42. Therefore, the relay valve 40, which receives the air pressure signal from the fourth circuit 64, is maintained off, so that the operation state of the parking brake of the tractor is maintained. In addition, the trailer control valve, which receives an air pressure signal from the third circuit 63, maintains the operating state of the parking brake of the trailer.

Further, since the compressed air is always supplied to the air tank 13 even when the first electromagnetic valve 41 is closed, there is a possibility that the compressed air leaks to the check valve 45 side due to valve deterioration or the like. At this time, the first solenoid valve 41 causes the second circuit 62 on the check valve 45 side to communicate with the relief circuit 39, and therefore releases the leaked compressed air to the atmosphere, thereby maintaining the pressure on the check valve 45 side at the atmospheric pressure. Further, the check valve 45 is not opened unless a predetermined valve opening pressure is applied thereto, and therefore, the closed state is maintained. In other words, the compressed air leaking from the first solenoid valve 41 may not raise the air pressure of the third circuit 63 and the fourth circuit 64 via the check valve 45, turn on the relay valve 40, and release the parking brake during operation. Therefore, the pressure of the air pressure signal in the third circuit 63 and the fourth circuit 64 is maintained at the same atmospheric pressure immediately before the power loss even after the power loss, and therefore, stability and reliability are high.

Next, a case where the ECU21 loses power when the parking brake is in the released state will be described.

Since the parking brake is in the released state, immediately before the power supply is lost, the first solenoid valve 41 is opened or closed after the pressure is adjusted, and the second solenoid valve 42 is closed, so that the third circuit 63 and the fourth circuit 64 are maintained at the predetermined air pressure. When the power is lost at this time and both the first solenoid valve 41 and the second solenoid valve 42, which are normally closed, are closed and turned off, a prescribed air pressure immediately before the power is lost is maintained in the third circuit 63 and the fourth circuit 64 interposed between the check valve 45 and the second solenoid valve 42. Therefore, the relay valve 40 that receives the air pressure signal of the predetermined air pressure from the fourth circuit 64 is kept open, and the parking brake of the tractor is kept released. In addition, the trailer control valve, which receives an air pressure signal from the third circuit 63, maintains the released state of the parking brake of the trailer.

Although the first solenoid valve 41 communicates the second circuit 62 on the check valve 45 side with the release circuit 39 when closed, the check valve 45 does not allow air to flow from the third circuit 63 to the second circuit 62, so that the air pressure in the third circuit 63 and the fourth circuit 64 does not drop, and the parking brake in the released state is not likely to be actuated. Therefore, the air pressure signals of the third and

fourth circuits

63 and 64 are maintained at the same air pressure immediately before the power loss even after the power loss, and thus are stable and highly reliable.

In addition, although the released state may be maintained when the parking brake is in the released state, the parking brake may be actuated after the vehicle is moved to an appropriate position. That is, the relay valve 40 is connected to the fifth circuit 65 branched from the fourth circuit 64, and the release valve 101 is connected thereto. If the parking brake is in the released state when the ECU21 loses power, the parking brake is also held in the released state after the loss of power, but when the release valve 101 is opened, the fifth circuit 65, the fourth circuit 64, and the third circuit 63 are released to the atmospheric pressure. This allows the parking brake of the tractor to be switched from the released state to the activated state, and the parking brake of the trailer to be switched from the released state to the activated state, while maintaining the activated state.

According to the present embodiment, the following effects can be obtained.

(1) Since the first solenoid valve 41 and the second solenoid valve 42 are normally closed solenoid valves, when the ECU21 that controls the opening/closing of these solenoid valves loses power, the air pressure between the first solenoid valve 41 and the second solenoid valve 42 immediately before the loss of power is maintained as the pressure of the air pressure signal between the first solenoid valve 41 and the second solenoid valve 42. Therefore, the operation of the relay valve 40, which inputs the air pressure signal of the fourth circuit 64 as the control pressure signal of the fifth circuit 65, is maintained. This enables the operating state of the parking brake to be maintained even if the ECU21 that controls the parking brake loses its power supply.

(2) The parking brake held in the released state by the air pressure signal having the pressure of the compressed air can be brought into the activated state by the operation of the release valve 101.

(3) The parking brake is released when the air pressure rises, and is operated when the air pressure is atmospheric pressure. Since the first solenoid valve 41 is a three-way valve and the check valve 45 is provided downstream of the first solenoid valve 41, the parking brake is not likely to be released by an increase in air pressure when the first solenoid valve 41 is closed.

(4) Although the first solenoid valve 41 is a three-way valve, the sealing force of the check valve 45 can keep the air pressure on the second solenoid valve 42 side higher than the air pressure on the first solenoid valve 41 side. Therefore, even if the ECU21 loses power and the first solenoid valve 41 and the second solenoid valve 42 are both closed, the pressure of the air pressure signal is maintained the same before and after the loss of power. That is, the air pressure holding mechanism is constituted by the check valve 45 and the second electromagnetic valve 42.

When the first solenoid valve 41 is closed, even if compressed air leaks from the first solenoid valve 41, the leaked compressed air is guided to the port of the first solenoid valve 41 that is open to the atmosphere by the one-way valve 45. This prevents the air pressure on the second solenoid valve 42 side from rising, and the parking brake once in the activated state is not suddenly released.

(5) By operating the third solenoid valve 43, the operating state of the parking brake of the tractor and the operating state of the parking brake of the trailer can be set to different states. For example, by cutting off the air pressure signal to the relay valve 40 by the third solenoid valve 43, only the parking brake of the trailer can be released in a state where the parking brake of the tractor is activated, and only the parking brake of the tractor can be checked. As described in detail, the third solenoid valve 43 can be opened after the parking brake of the tractor and the trailer is operated, so that the compressed air can be supplied to the trailer control valve and the compressed air cannot be supplied to the relay valve 40. Thus, the parking brake of the trailer can be released in a state where the parking brake of the tractor is actuated.

(second embodiment)

A second embodiment embodying the air supply circuit will be described with reference to fig. 2. The signal circuit 60A of the present embodiment is different from the signal circuit 60 of the first embodiment. For convenience of explanation, the same components as those of the first embodiment are denoted by the same reference numerals, and detailed explanation thereof is omitted.

As shown in fig. 2, in the present embodiment, the air supply circuit 10 includes a supply flow path 50 and a signal circuit 60A for transmitting an air pressure signal, as in the first embodiment.

The signal circuit 60A includes the first solenoid valve 41A between the first circuit 61 and the third circuit 63. The first solenoid valve 41A is a normally closed two-way two-position solenoid valve, and is controlled to be opened/closed by turning on/off the power supply from the wiring E62. The first solenoid valve 41A is disposed in the sealing position shown in fig. 2 when closed, and disposed in the communication position when opened. The first solenoid valve 41A blocks the connection between the first circuit 61 and the third circuit 63 in the sealed position, and connects the first circuit 61 and the third circuit 63 in the communication position. The branch circuit 63A of the third circuit 63 is connected to the relief circuit 39 and the sixth circuit 66 via the quick release valve 46.

The quick release valve 46 is connected to the branch circuit 63A, the release circuit 39, and the sixth circuit 66. When the air pressure of the branch circuit 63A is lower than a predetermined pressure, the quick release valve 46 connects the release circuit 39 and the sixth circuit 66. On the other hand, when the air pressure of the branch circuit 63A is equal to or higher than the predetermined pressure, the quick release valve 46 connects the third circuit 63 to the sixth circuit 66 via the branch circuit 63A.

The case where the ECU21 loses power in the present embodiment will be described.

Immediately before the power supply is lost, the first solenoid valve 41A is closed, the second solenoid valve 42 is opened or closed after being opened to the atmosphere, and thus the third circuit 63 and the fourth circuit 64 are opened to the atmosphere. When the power is lost at this time, both the first solenoid valve 41A and the second solenoid valve 42 are closed to become off, and the atmospheric pressure immediately before the power is lost is maintained in the third circuit 63 and the fourth circuit 64 interposed between the first solenoid valve 41A and the second solenoid valve 42. Therefore, the relay valve 40, which receives the air pressure signal from the fourth circuit 64 via the fifth circuit 65, is maintained off, so that the operating state of the parking brake of the tractor is maintained. When the pressure of the branch circuit 63A is lower than a predetermined pressure, the quick release valve 46 connects the sixth circuit 66 and the release circuit 39. Thus, receipt of atmospheric pressure from the sixth circuit 66 allows the operating state of the parking brakes of the trailer to be maintained.

Further, when the parking brake is in operation, compressed air is always supplied from the air tank 13 even if the first electromagnetic valve 41A is closed, and therefore there is a possibility that compressed air leaks into the third circuit 63 due to valve deterioration or the like. At this time, the quick release valve 46 releases air, which is applied from the branch circuit 63A at a pressure lower than the working pressure and lower than a predetermined pressure, to the release circuit 39. Therefore, even if compressed air leaks from the first solenoid valve 41A, the pressure of the third circuit 63 can be maintained at a pressure lower than the operating pressure of the quick release valve 46. Further, since the operating pressure of the quick release valve 46 is lower than the operating pressure of the relay valve 40, the air pressure of the third circuit 63 and the fourth circuit 64 may not be increased by the leaked compressed air, and the parking brake during operation may not be released. Therefore, the air pressure signals of the third and

fourth circuits

63 and 64 are maintained at the same atmospheric pressure even after the power loss as immediately before the power loss, and are stable and highly reliable.

Immediately before the power supply is lost, the first solenoid valve 41A is opened or closed after the pressure is adjusted, and the second solenoid valve 42 is closed, so that the third circuit 63 and the fourth circuit 64 are maintained at the prescribed air pressure. When the power is lost at this time, both the first solenoid valve 41A and the second solenoid valve 42 are closed to become off, and the air pressure immediately before the power is lost is maintained in the third circuit 63 and the fourth circuit 64 interposed between the first solenoid valve 41A and the second solenoid valve 42. At this time, the communication between the branch circuit 63A and the sixth circuit 66 by the quick release valve 46 based on the air pressure signal of the branch circuit 63A is also maintained. Therefore, the relay valve 40, which receives the air pressure signal from the fourth circuit 64 via the fifth circuit 65, is maintained on, so that the parking brake released state of the tractor is maintained. The quick release valve 46, when the branch circuit 63A is equal to or higher than a predetermined pressure, connects the branch circuit 63A and the sixth circuit 66. Thus, the trailer control valve receiving the air pressure signal from the branch circuit 63A maintains the released state of the parking brake of the trailer.

Further, since the compressed air is always supplied from the air tank 13 even when the first electromagnetic valve 41A is closed, there is a possibility that the compressed air leaks into the third circuit 63 due to deterioration of the valve or the like. However, even if the compressed air leaks into the third circuit 63, the air pressure of the third circuit 63 and the fourth circuit 64 to which the compressed air is originally supplied is maintained, and the released state of the parking brake is maintained. In other words, the parking brake in the released state is not likely to be operated due to a decrease in air pressure of the third circuit 63 and the fourth circuit 64. Therefore, the air pressure signals of the third and

fourth circuits

Further, as in the first embodiment, the release valve 101 is opened, whereby the fifth circuit 65, the fourth circuit 64, and the third circuit 63 are released to the atmospheric pressure. This allows the parking brake of the tractor to be switched from the released state to the activated state, and the parking brake of the trailer to be switched from the released state to the activated state, while maintaining the activated state.

According to the present embodiment, in addition to the effects (1) to (3) described in the first embodiment, the following effect can be obtained.

(6) Since the air pressure signal is applied as the control pressure signal to the relay valve 40 via the quick release valve 46, when the first electromagnetic valve 41A and the second electromagnetic valve 42 are closed due to the ECU21 losing power, the control pressure signal to the relay valve 40 is maintained in the state before the loss.

Further, when the first solenoid valve 41A is closed, even if compressed air leaks from the first solenoid valve 41A, the control pressure signal is maintained at the atmospheric pressure as long as the air pressure signal between the first solenoid valve 41A and the second solenoid valve 42 does not rise to the operating pressure of the quick release valve 46. Even if air pressure equal to or lower than the operating pressure is slowly applied to the quick release valve 46, the control pressure signal does not rise to the operating pressure because the air pressure leaks to the release circuit 39.

(7) The trailer control valve is supplied with an air pressure signal via a quick release valve 46. When compressed air is not supplied to the trailer control valve, even if compressed air leaks from the first solenoid valve 41A and a pressure lower than the operating pressure is applied to the air pressure signal, the quick release valve 46 is opened to the atmosphere, and therefore the parking brakes of the tractor and the trailer are not released.

(third embodiment)

A third embodiment embodying the air supply circuit will be described with reference to fig. 3. The present embodiment is a mode for a tractor (a single vehicle) when not towing a tractor, and is different from the first embodiment mainly in that the signal circuit 60B does not include the third electromagnetic valve 43.

As shown in fig. 3, in the present embodiment, the air supply circuit 10 includes a supply flow path 50 and a signal circuit 60B for transmitting an air pressure signal, as in the first embodiment.

The signal circuit 60B includes the first solenoid valve 41, the check valve 45, and the second solenoid valve 42 in this order from the 13 th port P13 to the release circuit 39. The first circuit 61 extends from the 13 th port P13 to the first solenoid valve 41, the second circuit 62 extends from the first solenoid valve 41 to the check valve 45, the fourth circuit 64 extends from the check valve 45 to the second solenoid valve 42, and the second solenoid valve 42 is connected to the release circuit 39. The present embodiment is not provided with the third circuit 63 in the first embodiment. A signal air pressure sensor 47 that detects air pressure is connected to the fourth circuit 64. The fourth circuit 64 branches off a fifth circuit 65. The fifth circuit 65 is connected to the relay valve 40, and is connected to the release valve 101 via a 101 th port P101.

The air supply circuit 10 of the present embodiment does not have a mechanism for releasing only the parking brake of the trailer for inspection, which is included in the first embodiment. Therefore, the operation of the air supply circuit 10 is the same as that in the first embodiment when the third electromagnetic valve 43 is closed and no inspection is performed, and therefore, the description thereof is omitted.

According to the present embodiment, in addition to the effects (1) to (4) described in the first embodiment, the following effect can be obtained.

(8) In a tractor (a single vehicle) when the tractor is not towed, the structure of the air supply circuit 10 can be made simpler than the structure of the air supply circuit 10 in a tractor when the tractor is towed.

(fourth embodiment)

A fourth embodiment embodying the air supply circuit will be described with reference to fig. 4. The present embodiment differs from the second embodiment in that it is a mode for a tractor (a single vehicle) when not towing a trailer.

As shown in fig. 4, in the present embodiment, the air supply circuit 10 includes a supply flow path 50 and a signal circuit 60C for transmitting an air pressure signal, as in the first embodiment.

The signal circuit 60C is different from the signal circuit 60A of the second embodiment in that: the third solenoid valve 43 is not provided, and the branch circuit 63A is not provided, and instead, the quick release valve 46 is connected to a middle portion of a fifth circuit 65 that branches from the fourth circuit 64.

To describe in detail, the signal circuit 60C includes the first solenoid valve 41 and the second solenoid valve 42 between the 13 th port P13 and the relief circuit 39. The first circuit 61 extends from the 13 th port P13 to the first solenoid valve 41, the fourth circuit 64 extends from the first solenoid valve 41 to the second solenoid valve 42, and the second solenoid valve 42 is connected to the release circuit 39. The signal air pressure sensor 47 is connected to the fourth circuit 64. A fifth circuit 65 branches off from the fourth circuit 64. In the fifth circuit 65, a quick release valve 46 is connected between the relay valve 40 and the 101 th port.

The quick release valve 46 is connected to the upstream side of the fifth circuit 65, the release circuit 39, and the downstream side of the fifth circuit 65. When the air pressure on the upstream side of the fifth circuit 65 (the fourth circuit 64) is lower than a predetermined pressure, the quick release valve 46 connects the release circuit 39 to the downstream side of the fifth circuit 65 (the relay valve 40). On the other hand, when the air pressure on the upstream side of the fifth circuit 65 (the fourth circuit 64) is equal to or higher than a predetermined pressure, the quick release valve 46 connects the upstream side of the fifth circuit 65 to the downstream side of the fifth circuit 65.

The air supply circuit 10 of the present embodiment does not have a mechanism for releasing only the parking brake of the trailer for inspection, which is included in the second embodiment. Therefore, the operation of the air supply circuit 10 is substantially the same as that when the third electromagnetic valve 43 is closed and no inspection is performed in the second embodiment, except for the relationship between the quick release valve 46 and the fifth circuit 65.

The case where the ECU21 loses power when the parking brake is in the operating state will be described.

First, when the parking brake is in an activated state, the ECU21 closes the first solenoid valve 41A and opens the second solenoid valve 42 or closes the second solenoid valve after opening to the atmosphere. Thereby, the fourth circuit 64 is connected to the release circuit 39, and the air pressure signal is maintained at atmospheric pressure. The atmospheric pressure signal does not operate the relay valve 40, and compressed air is not supplied from the second flow path 52, the third flow path 53, and the fourth flow path 54 to the brake chamber, so the brake chamber operates the parking brake.

Thereafter, when the ECU21 loses power, since the compressed air is always supplied from the air tank 13 even if the first electromagnetic valve 41A is closed, the compressed air may leak to the fourth circuit 64 due to deterioration of the valve or the like. At this time, the quick release valve 46 releases air, which is applied from the fourth circuit 64 at a pressure lower than the working pressure and is lower than a predetermined pressure, to the release circuit 39. Therefore, even if compressed air leaks from the first solenoid valve 41A, the pressure of the fourth circuit 64 can be maintained at a pressure lower than the operating pressure of the quick release valve 46. Therefore, there is no fear that the relay valve 40 is actuated to release the parking brake being actuated.

First, when the parking brake is in the released state, the ECU21 opens the first solenoid valve 41A and closes the second solenoid valve 42. Thus, an air pressure signal based on the air pressure of the compressed air from the air tank 13 is maintained in the fourth circuit 64, and the air pressure signal of the fourth circuit 64 operates the relay valve 40 via the quick release valve 46 and the fifth circuit 65. The relay valve 40 supplies compressed air from the air tank 13 to each brake chamber via the second flow path 52, the third flow path 53, and the fourth flow path 54 to release the parking brake.

Thereafter, when the ECU21 loses power, both the first solenoid valve 41A and the second solenoid valve 42 close to become closed, and the air pressure immediately before the loss of power is maintained in the fourth circuit 64 interposed between the first solenoid valve 41A and the second solenoid valve 42. At this time, the communication between the upstream and downstream of the fifth circuit 65 by the quick release valve 46 based on the air pressure signal of the fourth circuit 64 is also maintained. Therefore, the relay valve 40, which receives the air pressure signal from the fourth circuit 64 via the fifth circuit 65, is maintained on, so that the parking brake released state of the tractor is maintained.

According to the present embodiment, in addition to the effects (1) to (4) described in the first embodiment and the effects (6) and (7) described in the second embodiment, the following effects can be obtained.

(9) In a tractor (a single vehicle) when the tractor is not towed, the structure of the air supply circuit 10 can be made simpler than the structure of the air supply circuit 10 in a tractor when the tractor is towed.

(fifth embodiment)

A fourth embodiment embodying the air supply circuit will be described with reference to fig. 5. The present embodiment differs from the first embodiment in the third electromagnetic valve 43 and the check valve 45.

As shown in fig. 5, the third solenoid valve 43A provided in the signal circuit 60 is a solenoid valve for releasing only the parking brake of the trailer and performing a check. The third solenoid valve 43A is normally maintained open and closed at the time of inspection. The third solenoid valve 43A is a normally closed two-way two-position solenoid valve, and is controlled to be opened/closed via a wiring E64. The third solenoid valve 43A is disposed in a sealing position shown in fig. 5 when closed, and disposed in a communication position when opened. The third solenoid valve 43A blocks communication between the third circuit 63 and the fourth circuit 64 in the sealed position, and communicates the third circuit 63 and the fourth circuit 64 in the communication position.

The check valve 45A provided in the signal circuit 60 is a check valve with a spring for preventing the flow of air leaking from the normally closed first electromagnetic valve 41 and preventing the rise of the air pressure signal of the relay valve 40.

The operation of the air supply circuit 10 will be described.

First, when the parking brake is changed from the activated state (on state) to the deactivated state (off state), the ECU21 opens the first solenoid valve 41 and the third solenoid valve 43A and closes the second solenoid valve 42. As a result, an air pressure signal based on the air pressure of the compressed air from the tank 13 is maintained in the second circuit 62, the third circuit 63, and the fourth circuit 64, and the relay valve 40 is operated by the air pressure signal of the fourth circuit 64 via the fifth circuit 65. The relay valve 40 supplies the compressed air from the air tank 13 to each brake chamber via the second flow path 52, the third flow path 53, and the fourth flow path 54. The ECU21 detects the air pressure in the third circuit 63 by the signal air pressure sensor 47, and detects the air pressures in the third flow path 53 and the fourth flow path 54 by the supply air pressure sensor 48. When the detected pressures of the signal air pressure sensor 47 and the supply air pressure sensor 48 reach the respective target pressures, the ECU21 closes the first solenoid valve 41 and closes the second solenoid valve 42 to maintain the air pressure signals of the second to fifth circuits 62 to 65, thereby maintaining the parking brake in the released state. Further, the air pressure signals of the second to fifth circuits 62 to 65 are set to the atmospheric pressure by opening the second solenoid valve 42 and the third solenoid valve 43A in a state where the first solenoid valve 41 is closed, whereby the air pressures of the second flow passage 52, the third flow passage 53, and the fourth flow passage 54 are set to the atmospheric pressure, and the parking brake is set to the operating state. On the other hand, when the detected pressure of either one of the signal air pressure sensor 47 and the supply air pressure sensor 48 is less than the corresponding target pressure, the ECU21 closes the second electromagnetic valve 42 and then opens the first electromagnetic valve 41 and the third electromagnetic valve 43A, so that the compressed air from the air tank 13 is supplied again to the second circuit 62, the third circuit 63, and the fourth circuit 64 as the air pressure signal. Accordingly, the air pressure in the second flow path 52, the third flow path 53, and the fourth flow path 54 is adjusted to be maintained at the target pressure, and the compressed air of a predetermined pressure is supplied to the brake chamber to release the parking brake of the tractor. In addition, compressed air of a target pressure is supplied to the trailer control valve to release the parking brake of the trailer.

Next, when the parking brake is changed from the released state to the activated state, the ECU21 closes the first solenoid valve 41 and opens the second solenoid valve 42 and the third solenoid valve 43A. Thereby, the third circuit 63 and the fourth circuit 64 are connected to the relief circuit 39, so that the air pressure signal is maintained at the atmospheric pressure. The atmospheric pressure signal deactivates the relay valve 40 so that the parking brake is not actuated by the brake chamber supplied with compressed air from the second flow path 52, the third flow path 53, and the fourth flow path 54. The ECU21 detects the air pressure in the third circuit 63 by the signal air pressure sensor 47, and detects the air pressures in the third flow path 53 and the fourth flow path 54 by the supply air pressure sensor 48. The ECU21 confirms whether the detected pressures of the signal air pressure sensor 47 and the supply air pressure sensor 48 are atmospheric pressures, respectively. The ECU21 may close the second electromagnetic valve 42 and the third electromagnetic valve 43A when the detected pressure is atmospheric pressure. At this time, when the detected pressure of either one of the signal air pressure sensor 47 and the supply air pressure sensor 48 is no longer at atmospheric pressure, the ECU21 opens the second solenoid valve 42 and the third solenoid valve 43A to reach atmospheric pressure. Thereby, the air pressure of the third flow passage 53 and the fourth flow passage 54 is maintained at the atmospheric pressure. Thus, the brake chamber is maintained at atmospheric pressure, thereby operating the parking brake of the tractor. In addition, the air pressure of the trailer control valve is made atmospheric pressure, thereby operating the parking brake of the trailer.

In addition, the air supply circuit 10 can release only the parking brake of the trailer for inspection. In the inspection, the ECU21 first opens the second solenoid valve 42 and the third solenoid valve 43A to set the parking brake of the tractor and the trailer in an operating state (on). Then, the third solenoid valve 43A is closed to maintain the air pressure in the fourth circuit 64, thereby maintaining the operating state of the parking brake of the tractor. Next, when the first solenoid valve 41 is opened, compressed air is supplied to the port P31 via the third circuit 63 and the sixth circuit 66, and the parking brake of the trailer is released. This allows the parking brake of the trailer to be released, and only the parking brake of the tractor can be checked. During the inspection, even if the power supply is lost, the state in which only the parking brake of the tractor is operated can be maintained. The check here is a check as to whether or not the tractor to which the trailer is connected can be kept in a stopped state on a slope having a gradient of 12% only by the parking brake of the tractor in a state where the parking brake of the trailer is released.

The operation of the present embodiment will be described.

In addition, the ECU21 may lose power due to disconnection or the like. At this time, it is necessary to maintain the released state or the operated state at the time of power loss to avoid the difference between the operation state of the parking brake and the operation of the driver immediately before the power loss. That is, it is necessary to prevent the parking brake from being switched from the released state to the actuated state or from being switched from the actuated state to the released state due to the loss of power to the ECU 21. In this regard, according to the present embodiment, even if the ECU21 loses power due to disconnection or the like, the operating state of the parking brake is maintained as the operating state at the time of loss of power. In the following description, when the parking brake of the trailer is not checked, the normally closed third solenoid valve 43A is opened to communicate the third circuit 63 with the fourth circuit 64.

Immediately before the power loss, the first solenoid valve 41 is closed, the second solenoid valve 42 is opened or closed after being opened to the atmosphere, and thus the second circuit 62, the third circuit 63, and the fourth circuit 64 are all opened to the atmosphere. When the power supply is lost at this time, the normally closed first solenoid valve 41, second solenoid valve 42, and third solenoid valve 43A are all closed to become closed, so that the atmospheric pressure immediately before the power supply is lost is maintained in the third circuit 63 and fourth circuit 64 interposed between the check valve 45A and second solenoid valve 42. Therefore, the relay valve 40, which receives the air pressure signal from the fourth circuit 64, is maintained off, so that the operation state of the parking brake of the tractor is maintained. In addition, the trailer control valve, which receives an air pressure signal from the third circuit 63, maintains the operating state of the parking brake of the trailer.

Further, since the compressed air is always supplied to the air tank 13 even when the first electromagnetic valve 41 is closed, there is a possibility that the compressed air leaks to the check valve 45A side due to valve deterioration or the like. At this time, the first solenoid valve 41 causes the second circuit 62 on the check valve 45A side to communicate with the relief circuit 39, and therefore, the leaked compressed air is released to the atmosphere to maintain the pressure on the check valve 45A side at the atmospheric pressure. The check valve 45A is not opened when a predetermined valve opening pressure is not applied, and therefore, the closed state is maintained. In other words, the compressed air leaking from the first solenoid valve 41 may not raise the air pressure in the third circuit 63 and the fourth circuit 64 via the check valve 45A, and open the relay valve 40 to release the parking brake during operation. Therefore, the air pressure signals of the third circuit 63 and the fourth circuit 64 are maintained at the same atmospheric pressure immediately before the power loss even after the power loss, and thus are stable and highly reliable.

Since the parking brake is in the released state, immediately before the power supply is lost, the first solenoid valve 41 is opened or closed after the pressure is adjusted, the second solenoid valve 42 is closed, and the third solenoid valve 43A is opened, so that the third circuit 63 and the fourth circuit 64 are maintained at the predetermined air pressure. When both the first solenoid valve 41 and the second solenoid valve 42, which are normally closed by the loss of power at this time, are closed and turned off, a predetermined air pressure immediately before the loss of power is maintained in the third circuit 63 and the fourth circuit 64 interposed between the check valve 45A and the second solenoid valve 42. Therefore, the relay valve 40 that receives the air pressure signal of the predetermined air pressure from the fourth circuit 64 is kept open, and the parking brake of the tractor is kept released. In addition, the trailer control valve, which receives an air pressure signal from the third circuit 63, maintains the released state of the parking brake of the trailer.

Further, although the first solenoid valve 41 communicates the second circuit 62 on the check valve 45A side with the release circuit 39 when closed, the check valve 45A does not allow air to flow from the third circuit 63 to the second circuit 62, so that the air pressure of the third circuit 63 and the fourth circuit 64 does not drop, and there is no fear that the parking brake in the released state is actuated. Therefore, the air pressure signals of the third and

fourth circuits

(5) The operating state of the parking brake of the tractor and the operating state of the parking brake of the trailer can be set to different states by the operation of the third solenoid valve 43A. For example, by cutting off the air pressure signal to the relay valve 40 by the third solenoid valve 43A, only the parking brake of the trailer can be released in a state where the parking brake of the tractor is activated, and only the parking brake of the tractor can be checked. When described in detail, after the parking brakes of the tractor and the trailer are operated, the third electromagnetic valve 43A is closed, thereby enabling the supply of compressed air to the trailer control valve and disabling the supply of compressed air to the relay valve 40. This enables the parking brake of the trailer to be released while the parking brake of the tractor is activated.

(10) Since the third electromagnetic valve 43A is a normally closed electromagnetic valve, even if air leaks from the first electromagnetic valve 41 when the ECU21 that controls the opening/closing of the electromagnetic valve loses power supply, the application of an air pressure signal to the relay valve 40 can be prevented by the normally closed third electromagnetic valve 43A.

(other embodiments)

The above embodiments can be modified and implemented as follows. The above embodiments and the following modifications can be combined and implemented within a range not technically contradictory to each other.

In the above embodiments, the case where the supply air pressure sensor 48 is provided downstream of the relay valve 40 in the supply flow path 50 and the signal air pressure sensor 47 is provided in the third circuit 63 or the fourth circuit 64 of the signal circuit 60 is exemplified. However, the present invention is not limited to this, and the supply air pressure sensor and the signal air pressure sensor may be provided in either one of them as long as the operating state of the parking brake can be controlled. Further, if detailed pressure control is not required, control may be performed by time or the like without providing both the supply air pressure sensor and the signal air pressure sensor. This can simplify the structure of the air supply circuit.

In the sixth circuit 66, when there is no quick release valve between the third circuit 63 and the 31 st port P31, a quick release valve may be provided between the third circuit 63 and the 31 st port P31.

In the fifth circuit 65, in the case where there is no quick release valve between the fourth circuit 64 and the relay valve 40, a quick release valve may be provided between the fourth circuit 64 and the relay valve 40.

As shown in fig. 6, in the second embodiment, the third solenoid valve 43 of the signal circuit 60 may be replaced with the normally closed third solenoid valve 43A. The air pressure of the third and

fourth circuits

63, 64 is normally adjusted by the first solenoid valve 41 or the second solenoid valve 42 by opening the third solenoid valve 43A. On the other hand, when the ECU21 loses power and the second solenoid valve 42 and the third solenoid valve 43A are closed, the air pressure immediately before the loss of power is maintained in the third circuit 63 and the fourth circuit 64, and the operating states of the parking brake of the tractor and the parking brake of the trailer are maintained. In addition, even if the compressed air from the air tank 13 leaks at the first electromagnetic valve 41, the third circuit 63 and the fourth circuit 64 are shut off by the third electromagnetic valve 43A, and the third circuit 63 is connected to the release circuit 39. Therefore, the air pressure of the third circuit 63 and the fourth circuit 64 is not increased by the leaked compressed air, and the parking brake during operation is not released.

As shown in fig. 7, in the first embodiment, the check valve 45 of the signal circuit 60 may be replaced with the fourth solenoid valve 44 that is normally closed. The air pressure of the third and

fourth circuits

63, 64 is normally adjusted by the first solenoid valve 41 or the second solenoid valve 42 by opening the fourth solenoid valve 44. On the other hand, when the ECU21 loses power and the fourth solenoid valve 44 and the second solenoid valve 42 are closed, the air pressure immediately before the loss of power is maintained in the third circuit 63 and the fourth circuit 64, and the operating states of the parking brake of the tractor and the parking brake of the trailer are maintained. In addition, even if the compressed air from the air tank 13 leaks at the first solenoid valve 41, the space between the second circuit 62 and the third circuit 63 is shut off by the fourth solenoid valve 44, and the second circuit 62 is connected to the release circuit 39. Therefore, the air pressure of the third circuit 63 and the fourth circuit 64 is not increased by the leaked compressed air, and the parking brake during operation is not released. In the fifth embodiment, the check valve 45 of the signal circuit 60 may be replaced with a fourth solenoid valve that is normally closed.

In the first and second embodiments described above, the case where the air pressure signal is transmitted from the signal circuit 60 to the parking brake of the trailer is exemplified. However, the present invention is not limited to this, and an air pressure signal to be transmitted to the parking brake of the trailer may be acquired from the second flow path 52 of the supply flow path 50.

As shown in fig. 8, a 31 st port P31 connected to the trailer control valve may be provided in a branch flow path 52A branching from the second flow path 52. At this time, the third solenoid valve 43 may be disposed downstream of the branch flow passage 52A of the second flow passage 52 as a third solenoid valve 43B, excluding the signal circuit 60. Since the third solenoid valve 43B is a normally open solenoid valve, both the tractor parking brake and the trailer parking brake normally operate in accordance with the output of the relay valve 40. Thus, the action of the parking brake of the tractor is synchronized with the action of the parking brake of the trailer. On the other hand, for the purpose of inspection, the operation of the parking brake of the tractor and the operation of the parking brake of the trailer can be made asynchronous by closing the third solenoid valve 43. For example, the parking brake of the trailer can be released in a state where the parking brake of the tractor is actuated.

As shown in fig. 9, the normally open third electromagnetic valve 43B shown in fig. 8 may be replaced with a normally closed third electromagnetic valve 43C. Since the third solenoid valve 43C is a normally closed solenoid valve, both the tractor parking brake and the trailer parking brake are normally operated by the output of the relay valve 40 by opening the third solenoid valve 43C. Thus, the action of the parking brake of the tractor is synchronized with the action of the parking brake of the trailer. On the other hand, for the purpose of inspection, the operation of the parking brake of the tractor and the operation of the parking brake of the trailer can be made asynchronous by closing the third solenoid valve 43C. When the ECU21 loses power and the third solenoid valve 43C is closed, the air pressure immediately before the power loss is maintained in the third flow passage 53 and the fourth flow passage 54, and the operating state of the parking brake of the tractor is maintained.

In each embodiment, the check valve 45 without a spring may be a check valve 45A with a spring. The check valve 45A with a spring may be a check valve 45 without a spring.

As shown in fig. 10, the check valve 45 of the signal circuit 60B in the third embodiment may be replaced with a normally closed fourth solenoid valve 44. The fourth solenoid valve 44 is normally opened to adjust the air pressure of the fourth circuit 64 by the first solenoid valve 41 or the second solenoid valve 42. On the other hand, when the ECU21 loses power and the fourth solenoid valve 44 is closed, the air pressure immediately before the loss of power is maintained in the fourth circuit 64 between the fourth solenoid valve 44 and the second solenoid valve 42, and the operating state of the parking brake of the tractor is maintained. In addition, even if the compressed air from the air tank 13 leaks at the first solenoid valve 41, the fourth solenoid valve 44 cuts off between the second circuit 62 and the fourth circuit 64, and the second circuit 62 is connected to the release circuit 39. Therefore, the leaked compressed air does not increase the air pressure of the fourth circuit 64 and may release the parking brake during operation.

In the above embodiments, the air supply circuit 10 has been described as being used only for a tractor or a coupled vehicle including a tractor and a trailer. As another embodiment, the air supply circuit may be used for other vehicles such as a car and a railway vehicle.

Description of the reference numerals

10: an air supply circuit; 13: a gas tank; 21: an ECU; 39: a release circuit; 40: a relay valve; 41. 41A: a first solenoid valve; 42: a second solenoid valve; 43. 43B: a third electromagnetic valve; 44: a fourth solenoid valve; 45: a one-way valve; 46: a quick release valve; 47: a signal air pressure sensor; 48: a supply air pressure sensor; 49: a release circuit; 49: an outlet port; 50: a supply flow path; 51: a first flow path; 52: a second flow path; 52A: a branch flow path; 53: a third flow path; 54: a fourth flow path; 60. 60A, 60B, 60C: a signal loop; 61: a first circuit; 62: a second loop; 63: a third circuit; 63A: a branch loop; 64: a fourth loop; 65: a fifth circuit; 66: a sixth loop; 101: the valve is released.

Claims

1. An air supply circuit is provided with:

a supply flow path having a relay valve between the air tank and a brake chamber for parking brake, the supply flow path supplying air;

a signal circuit having a normally closed first solenoid valve and a normally closed second solenoid valve arranged in series between the gas tank and a release circuit open to the atmosphere, the signal circuit being for transmitting an air pressure signal; and

a control device that controls switching of opening and closing of the first electromagnetic valve and switching of opening and closing of the second electromagnetic valve, respectively,

wherein an air pressure signal between the first solenoid valve and the second solenoid valve is applied to the relay valve as a control pressure signal for controlling the relay valve.

2. The air supply circuit of claim 1,

there is a release valve capable of releasing the control pressure signal applied to the relay valve to atmosphere.

3. The air supply circuit according to claim 1 or 2,

an air pressure maintaining mechanism is provided between the first solenoid valve and the relay valve, and when the first solenoid valve is closed, the air pressure maintaining mechanism does not transmit the air pressure from the first solenoid valve to the relay valve.

4. The air supply circuit of claim 3,

a check valve that allows air to flow from the first solenoid valve disposed on the tank side to the second solenoid valve disposed on the release circuit side is provided in the signal circuit,

the control pressure signal is an air pressure signal between the check valve and the second solenoid valve,

the first solenoid valve is a three-way valve that opens a space between the first solenoid valve and the check valve to the atmosphere when the first solenoid valve is closed.

5. The air supply circuit of claim 3,

the signal circuit is provided with a quick release valve,

the air pressure signal is applied as the control pressure signal to the relay valve via the quick release valve when the air pressure signal has an air pressure greater than or equal to a working pressure of the quick release valve, and atmospheric pressure is applied as the control pressure signal to the relay valve via the quick release valve when the air pressure signal has an air pressure less than the working pressure of the quick release valve.

6. The air supply circuit according to any one of claims 1 to 5,

the air supply circuit is connected to the brake chamber of the tractor and to the trailer control valve,

the signal circuit having a third solenoid valve, the signal circuit outputting the air pressure signal to the trailer control valve and applying the air pressure signal to the relay valve via the third solenoid valve,

the air supply circuit supplies the compressed air regulated by the relay valve to a brake chamber of the tractor.

7. The air supply circuit of claim 6,

the third electromagnetic valve is a normally closed electromagnetic valve,

the control device controls the switching of the opening and the closing of the third electromagnetic valve.

8. The air supply circuit of claim 6 or 7,

the air pressure signal is output to the trailer control valve via a quick release valve.